In quasi-chemical theory of solutions, the enthalpy of mixing of the system can be expressed, the fraction of B (Xb) in the system will be 0.0729
ΔH = XaXb (7500 Xa + 18200 Xb)
Bond energies are as:
eaa = -6.5 × 10⁻²⁰
ebb = -5.3 × 10⁻²⁰ J/mol
eab = -5.4 × 10⁻²⁰ J /mol
The charge in internal energy will be
Δe = eab - 1/2 (eaa + ebb)
Δe = -5.4 × 10⁻²⁰ J /mol - 1/2 (-6.5 × 10⁻²⁰ - (-5.3 × 10⁻²⁰ J/mol)
Δe = 6.4 × 10⁻²⁰
enthalpy of mixing will be
ΔH mix = N₀.Z.XaXbΔe
ΔH mix = 6.0221 × 10²³ × 4 × Xa.Xb × 6.4 × 10⁻²⁰ (2)
We have
ΔH = XaXb (7500 Xa + 18200 Xb) (1)
(1) = (2)
154.165 × 10³ = 7500 Xa + 18200 Xb
As Xa = 1 - Xb
put in above eq.
154.165 × 10³ = 7500 (1 - Xb) + 18200 Xb
146665 = 10700 Xb
Xb = 0.0729
So fraction of B(Xb) = 0.0729
(Complete question is attached)
You can also learn about the quasi-chemical theory from the following question:
https://brainly.com/question/14284453
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